During the development of the digital data system of this application and the above referenced application, it became apparent that improvements in the signal detection method may be helpful.
The digital data system of the present invention has the capability of allowing numerous remote terminals to augment a message at various remote locations around the system. As the number of remote terminals, upon the system, fluctuates, the average signal strength correspondingly fluctuates. These fluctuations in signal amplitude complicate the signal detection. Furthermore, the inherent attenuation of signals along the transmission line creates disparity in signal amplitude at any given point depending on the relative location of the remote terminal transmitting that message and the location of the distant receiver.
For example, the original data and clock signal which is transmitted by the transmitter 202 (FIG. 2) is received back at receiver 204 (FIG. 2) but at an attenuated level, due to the inherent signal loss along the transmission line. However, an identical logic level message which is added to the system at a remote terminal nearer the receiver will not travel as long on the transmission line, as an original message or logic level, and thereby will not experience as much signal amplitude attenuation. As a result, the signal at the receiver will have variations in amplitude. As stated earlier, these signal variations complicate the detection of the desired signals.
Consequently, there exists a need for advancement in signal detection schemes for digital data systems, which does not use absolute signal amplitude for the detection of signals.